Measurement of neopterin, TGF-β1 and ACE in the exhaled breath condensate of patients with sarcoidosis

Exhaled breath condensate (EBC) is a non-invasive method of sampling airway lining fluids in respiratory diseases. This may be useful in identifying exhaled biomarkers of granulomatous inflammation and pulmonary fibrosis in patients with sarcoidosis. The aim of this pilot study was to identify markers of granulomatous airway inflammation and disease activity including neopterin, transforming growth factor-beta(1) (TGF-beta(1)) and angiotensin converting enzyme (ACE) in EBC. EBC was collected from 16 patients with sarcoidosis and 22 healthy control subjects. EBC neopterin, and active-TGF-beta(1) were measured by ELISA. EBC-ACE activity was measured using a colorimetric assay. EBC neopterin was detectable in 3/20 controls and 7/16 patients with sarcoidosis. Patients with sarcoidosis had greater mean neopterin levels compared to control subjects (0.57 +/- 0.45 nmol l(-1) versus 0.41 +/- 0.22 nmol l(-1), p = 0.04). TGF-beta(1) was detectable in the EBC of all subjects and concentrations were higher in patients with sarcoidosis compared with controls (115.5 +/- 79.6 pg mol(-1) versus 82.3 +/- 16.2 pg mol(-1), p = 0.048). There was no difference in EBC ACE activity, which was only detectable in 3/20 healthy controls and 2/16 patients (p = 0.91). EBC markers of granulomatous inflammation are detectable at greater levels in patients with sarcoidosis compared to healthy controls subjects. Larger studies and development of sensitive assays are warranted to examine the disease correlates and predictive utility of these markers.